1. Field of the Invention
The present invention relates to a medium conveying apparatus for sequentially conveying media stacked on a medium container.
2. Description of the Related Art
Conventionally, there is an apparatus including a pickup roller that abuts the uppermost medium of stacked media and applies frictional force to the uppermost medium to convey the uppermost medium in a conveying direction. Japanese Patent Application Publication No. 2000-85997 discloses an image forming apparatus including a paper feed roller that sequentially feeds stacked sheets of paper from the uppermost sheet.
However, in the conventional apparatus, when a large number of media are stacked and the thickness of each of the media is not uniform in a width direction of the medium perpendicular to the conveying direction (e.g., when western envelopes with their flaps folded are conveyed in a direction parallel to a longitudinal direction of the envelopes), the uppermost medium tilts relative to a horizontal plane in a lateral direction that is parallel to the horizontal plane and perpendicular to the conveying direction, and thus abuts only one side of the pickup roller.
When the pickup roller conveys a medium while the medium abuts only one side of the pickup roller, the frictional force applied by the pickup roller to the medium is not uniform in the lateral direction. This causes skew of the medium and reduces accuracy in conveyance of the medium.